/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package com.hujinwen.flume.sink.elasticsearch;

import com.google.common.annotations.VisibleForTesting;
import org.apache.commons.lang.StringUtils;
import org.apache.commons.lang.time.FastDateFormat;
import org.apache.flume.Context;
import org.apache.flume.Event;
import org.apache.flume.conf.ComponentConfiguration;
import org.apache.flume.formatter.output.BucketPath;

import java.util.Calendar;
import java.util.Date;
import java.util.TimeZone;

/**
 * Default index name builder. It prepares name of index using configured
 * prefix and current timestamp. Default format of name is prefix-yyyy-MM-dd".
 */
public class TimeBasedIndexNameBuilder implements
        IndexNameBuilder {

    private static final String DATE_FORMAT = "dateFormat";
    private static final String TIME_ZONE = "timeZone";

    private static final String DEFAULT_DATE_FORMAT = "yyyy-MM-dd";
    private static final String DEFAULT_TIME_ZONE = "Etc/UTC";

    private FastDateFormat fastDateFormat = FastDateFormat.getInstance("yyyy-MM-dd",
            TimeZone.getTimeZone("Etc/UTC"));

    private String indexPrefix;

    @VisibleForTesting
    FastDateFormat getFastDateFormat() {
        return fastDateFormat;
    }

    /**
     * Gets the name of the index to use for an index request
     *
     * @param event Event for which the name of index has to be prepared
     * @return index name of the form 'indexPrefix-formattedTimestamp'
     */
    @Override
    public String getIndexName(Event event) {
        TimestampedEvent timestampedEvent = new TimestampedEvent(event);
        long timestamp = timestampedEvent.getTimestamp();
        String realIndexPrefix = BucketPath.escapeString(indexPrefix, event.getHeaders());
        return realIndexPrefix + '-' +
                fastDateFormat.format(timestamp);
    }

    /**
     * 获取指定天数的index name
     *
     * @param field  参考 calendar.add()
     * @param amount 参考 calendar.add()
     */
    public String getIndexName(int field, int amount) {
        final Calendar calendar = Calendar.getInstance();
        calendar.setTime(new Date());
        calendar.add(field, amount);

        return indexPrefix + "-" + fastDateFormat.format(calendar);
    }

    @Override
    public String getIndexPrefix(Event event) {
        return BucketPath.escapeString(indexPrefix, event.getHeaders());
    }

    @Override
    public void configure(Context context) {
        String dateFormatString = context.getString(DATE_FORMAT);
        String timeZoneString = context.getString(TIME_ZONE);
        if (StringUtils.isBlank(dateFormatString)) {
            dateFormatString = DEFAULT_DATE_FORMAT;
        }
        if (StringUtils.isBlank(timeZoneString)) {
            timeZoneString = DEFAULT_TIME_ZONE;
        }
        fastDateFormat = FastDateFormat.getInstance(dateFormatString,
                TimeZone.getTimeZone(timeZoneString));
        indexPrefix = context.getString(ElasticSearchSinkConstants.INDEX_NAME);
    }

    @Override
    public void configure(ComponentConfiguration conf) {
    }
}
